Utility meters are devices that, among other things, measure the consumption of a utility-generated commodity, such as electrical energy, gas, or water, by a facility, such as a residence, a factory, or a commercial establishment. Utility service providers employ utility meters to track customer usage of the utility-generated commodities for reasons including billing and demand forecasting of the commodity.
Electricity meters are utility meters configured to measure quantities related to the consumption of electrical energy by a facility or other load. In some instances, the electricity meter is received by a socket that is electrically connected to the utility-generated power source and to the electrical load of a customer. Electricity passes through current coils of the electricity meter as it flows from the power source to the customer's electrical load. The electricity meter monitors the total amount of electrical energy that is provided to the load via the current coils.
One type of undesirable condition in a meter and socket is known as a “hot socket.” A “hot socket” occurs when the socket that receives the electricity meter ceases to efficiently transfer electrical energy from the source to the electricity meter. In particular, as the socket ages, jaws within the socket may lose spring tension, such that a less reliable electrical connection exists between the socket and the electricity meter. Under certain conditions, the less reliable connection may cause micro-arcing between the socket and the electricity meter, which undesirably results in an increase in temperature of the socket and the electricity meter. If the socket and the electricity meter are subject to the hot socket condition for an extended time period, then damage may result to at least one of the socket and the electricity meter and the customer is likely to experience a service interruption. In addition, the heat from the hot socket represents I2R loss, which is inefficient. As a result, customers desire early and accurate detection of the hot socket condition so that time is available for a technician to take mitigating steps to correct the problem to avoid losses and/or an unplanned service interruption.
Methods and systems for detecting the hot socket condition are known, including sensors that detect heat in the area of the coil. However, these methods are not always as reliable as desired because the results can be easily misinterpreted. For example, it is difficult for most systems to differentiate between the hot socket condition and the large temperature rise that occurs from natural environmental conditions, such as solar loading. Solar loading, which has nothing to do with the hot socket condition, is where the electricity meter experiences a significant increase in temperature due to direct sunlight. Misinterpretation of the results of known methods and system for detecting the hot socket condition causes customer dissatisfaction due to the possibility of an unplanned electrical service interruption.
Thus, a continuing need exists to increase the performance of utility meters so that the utility service provider is able to accurately and reliably determine the operating state of the utility meter and, in particular, whether or not an electricity meter is presently experiencing the hot socket condition.